When Hans Selye was experimenting on rats by inflicting stress them either by injecting them with hormones or chemicals, making surgical incisions or exposing them to extreme temperatures, he noticed that the rats were all displaying the same group of symptoms. At first he believed that he had discovered a new hormone1; however, several years of further testing by injecting the rats with other substances, such as formaldehyde, revealed the same results. Even exposure to cold, cutting their spinal cords and forced exercise produced the same effects. The effects occurred in a predictable sequence that is now known as the General Adaptation Syndrome2 (GAS).

1. Hormones are molecules that act as chemical messengers. They are released by one part of the body and have an affect on another part of the body. They are often transported through the bloodstream.

2. In medicine and psychology the term syndrome refers to the association of several clinically recognizable features, signs (discovered by a physician), symptoms (reported by the patient), phenomena or characteristics which often occur together so that the presence of one feature alerts the physician to the presence of the others (source wikipedia

This article is an attempt to clear up some of the misconceptions on the internet regarding the Bannister's Fitness-Fatigue Model, the so-called "Dual Factor Theory". Although it is simply a model it has been used to design one size fits all programs due to a misconception that it attempts to explain training responses for a typical trainee. Such programs are nonsense and a proper explanation is needed to counter such misinformation. Programs are not built from these kinds of theoretical models. These models, instead, are built to try to understand responses to training.